class_docstr: Base Graph Model
class_docstr_tok: ["Base","Graph","Model"]
docstr: listwise model
docstr_tok: ["listwise","model"]
code: def bce_loss(self):
      """listwise model"""
      mask = L.cast(self.labels > 0.5, dtype="float32")
      mask.stop_gradients = True
  
      self.loss = L.log_loss(self.logits, mask, epsilon=1e-15)
      self.loss = L.reduce_mean(self.loss) * 2
      proba = L.sigmoid(self.logits)
      proba = L.concat([proba * -1 + 1, proba], axis=1)
      auc_out, batch_auc_out, _ = L.auc(
          input=proba, label=self.labels, curve="ROC", slide_steps=1
      )
  
      self.metrics = {
          "loss": self.loss,
          "auc": batch_auc_out,
      }
  
file_path: PGL/ogb_examples/linkproppred/ogbl-ppa/model.py
imports: import os
  import re
  import time
  from random import random
  from functools import reduce, partial
  import numpy
  import multiprocessing
  import paddle
  import paddle.fluid
  import paddle.fluid.layers
  from pgl.graph_wrapper import GraphWrapper
  from pgl.layers.conv import gcn, gat
label_desc: Use image node_id 4 for calling the BaseGraph obj's underlying member method code with example usage: obj.bce_loss() without return types